mineral

Pyrite

Iron Sulfide (FeS2)

Hardness: 6-6.5 (Mohs); Color: Pale brass-yellow to golden; Luster: Metallic; Crystal Structure: Isometric/Cubic; Cleavage: Poor/Indistinct; Specific Gravity: 4.8-5.0

Hardness: 6-6
Color: Pale brass-yellow to golden
Luster: Metallic

Identified June 25, 2026More mineral →

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Physical properties

Hardness: 6-6.5 (Mohs); Color: Pale brass-yellow to golden; Luster: Metallic; Crystal Structure: Isometric/Cubic; Cleavage: Poor/Indistinct; Specific Gravity: 4.8-5.0

Formation & geological history

Forms in diverse geological settings including hydrothermal veins, as an accessory mineral in igneous rocks, and by precipitation in sedimentary environments with low oxygen. Common in coal beds and as replacement fossils.

Uses & applications

Used historically to produce sulfuric acid and sulfur. Currently used in some lithium batteries, as a flux in glassmaking, and extensively as ornamental stone and jewelry (often sold as 'marcasite' in the trade).

Geological facts

Commonly known as 'Fool's Gold' because its color and weight frequently confused prospectors during the gold rush. Unlike gold, which is soft, pyrite is brittle and cannot be scratched by a fingernail.

Field identification & locations

Identify by its 'cubic' crystal habit, greenish-black streak (gold has a yellow streak), and sulfurous odor when struck or crushed. Widely found in Peru, Spain, and the USA.